Computed property for serialization

Hi there, Is there any way to make computed property for serialization?

The code down below produces a compilation error: e: org.jetbrains.kotlin.codegen.CompilationException: Back-end (JVM) Internal error: Failed to generate expression: KtNameReferenceExpression

but I expected it works properly:

@Serializable
data class Record(val id: String,
                  val sourceUrl: String,
                  val index: Int = indexFromUri(Uri.parse(sourceUrl)),
                  val name: String = nameFromUri(Uri.parse(sourceUrl))) {
}


fun indexFromUri(uri: Uri): Int {
    val lastComponent = uri.lastPathSegment?.substringAfterLast('/')
    return lastComponent?.take(2)?.toIntOrNull() ?: 0
}

fun nameFromUri(uri: Uri): String {
    val lastComponent = uri.lastPathSegment?.substringAfterLast('/')
    return lastComponent?.substring(3) ?: "No name"
}

Kotlin: 1.4.20 kotlinx-serialization-json: 1.0.1

[shanshin]

@shanshin Does it make sense to use @SerialName on a @Transient property?

No. Because @Transient properties are not serialized SerialName does not affect encoding/decoding. In the example above they are given as an example for clarity only.

[shanshin]

If the names of JSON attributes is fixed you can redefine the serial name of properties like this

@Serializable
data class Record(val id: String,
                  val sourceUrl: String,
                  @SerialName("index")
                  private val index_: Int? = null,
                  @SerialName("name")
                  private val name_: String? = null) {

    @Transient
    @SerialName("index_public")
    val index = index_ ?: indexFromUri(Uri.parse(sourceUrl))

    @Transient
    @SerialName("name_public")
    val name = name_ ?: nameFromUri(Uri.parse(sourceUrl))
} 

If you using equals/hashCode you should also override these functions to use index and name not index_, name_ properties, same with toString if necessary.

Another workaround is to create a custom KSerializer that will implement these intermediate computations.